“Obesity has traditionally been seen as the result of an imbalance between the amount of food we eat and how much we exercise,” wrote senior author Manolis Kellis, a professor of computer science and a member of MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) in a press release. “This view ignores the contribution of genetics to each individual’s metabolism.”

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Scientists identified the gene variant known as FTO, (found in 40% of Europeans and 5% of Africans) that is the link to obesity. People who carry this gene are heavier, and more likely to become obese. Obesity contributes to cardiovascular disease, type 2 diabetes, even cancer. More than half a billion people are affected worldwide.

Using a gene-editing technique known as CRISPR-Cas9, researchers found a way to manipulate the DNA sequence of FTO, effectively switching it into a gene variant that promotes fat burning, instead of fat storage.

The researchers were able to reverse the genetic signatures of obesity in human and mice cells. In mice, it “led to dramatic changes in whole-body energy balance, resulting in a reduction of body weight and all major fat stores, and complete resistance to a high-fat diet,” according to the study.

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Now that the causal variant underlying obesity has been identified, genome editing may be “a therapeutic avenue for individuals carrying the risk allele,” Kellis says. “But more importantly, the uncovered cellular circuits may allow us to dial a metabolic master switch for both risk and non-risk individuals, as a means to counter environmental, lifestyle, or genetic contributors to obesity.”

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Doctors have long recommended diet and exercise as the most effective one-two punch to melt away inches. Understanding the genetic association between the FTO locus and weight gain has added a third weapon to the arsenal, in the fight against obesity.

“By manipulating this new pathway, we could switch between energy storage and energy dissipation programs at both the cellular and the organismal level, providing new hope for a cure against obesity,” Kellis said.

CBSSF.com writer, producer Jan Mabry is also executive producer and host of The Bronze Report. She lives in Northern California. Follow her on Twitter @janmabr.